If you wait for a few confirmations you'll be fine.

The worst that could happen is you unwittingly participate in a scam on somebody else.  Scammer contacts you to buy your product.  Scammer contacts another guy to sell some product of similar value.  Scammer convinces him to send first-- to YOUR bitcoin address.  Scammer tells you he's paid you, you send him your product.  As far as you're concerned, everything is fine.  But unknown to you, some other guy just sent you bitcoins and is going to get nothing in return, and the scammer is going to get your product for free.  You could ensure this doesn't happen by asking the scammer to sign a message with the address he used to pay you.

This happens on IRC all the time when scammers buy cryptocurrencies.  They get a third party to paypal you, you send them the coins, they disappear, the third party then files a dispute with paypal, you're out the coins, the third party has a bunch of hassle, and both you and the third party think you're mad at each other, not even realizing that you were both communicating not with each other but with the scammer.  So neither of you even knows there was a scammer involved, you both just think it's the other guy who ripped you off.  But the truth is the scammer facilitated everything, telling you he's the third guy and telling the third guy he's you.

All of this being said-- it's 99% likely OP that the guy is on the up and up.  Most scammers don't send crypto, and don't offer to go first.  If it's less than a few hundred dollars worth, I would just believe him... as long as he does indeed send first.  This stuff I'm talking about is just possibilities to be aware of-- I don't think it's actually happening in your case OP.